There is a pretty good reason the QR and AA base fares are similar and yet the final ticket price is cheaper on AA. Probably not a "feature" as they say... but rather the other thing (a bug)
Step 1: search both fares on ITA and make a note of all the costs in the itemized brake down.
Step 2: Do a search for an AA eco fare on this same route w Matrix and look at the itemized amounts.
Which item is the same in step 1 and step 2?
Do you think it should be?